What if everyone, from a local expert to a renowned doctor, had an easy way of sharing their insights with you about any page on the web? What if you could add your own insights for others who are passing through?

Now you can. Today, we're launching Google Sidewiki, which allows you to contribute helpful information next to any webpage. Google Sidewiki appears as a browser sidebar, where you can read and write entries along the side of the page.

In developing Sidewiki, we wanted to make sure that you'll see the most relevant entries first. We worked hard from the beginning to figure out which ones should appear on top and how to best order them. So instead of displaying the most recent entries first, we rank Sidewiki entries using an algorithm that promotes the most useful, high-quality entries. It takes into account feedback from you and other users, previous entries made by the same author and many other signals we developed. If you're curious, you can read more on our Google Research Blog about the infrastructure we use for ranking all entries in real-time.

Under the hood, we have even more technology that will take your entry about the current page and show it next to webpages that contain the same snippet of text. For example, an entry on a speech by President Obama will appear on all webpages that include the same quote. We also bring in relevant posts from blogs and other sources that talk about the current page so that you can discover their insights more easily, right next to the page they refer to.

We're releasing Google Sidewiki as a feature of Google Toolbar (for Firefox and Internet Explorer) and we're working on making it available in Google Chrome and elsewhere too. We also have the first version of our API available today to let anyone work freely with the content that's created in Sidewiki.